This invention relates to a force detector and an acceleration detector to which the force detector is applied, and more particularly to a detector suitable for detection of multidimensional force or acceleration components. Further, this invention provides a method suitable for mass producing such detectors.
In the automobile industry or the machinery industry, there has been increased demand for detectors capable of precisely detecting a physical quantity such as force, acceleration or magnetism. Particularly, it is required to realize small detectors capable of detecting physical quantities every respective two-dimensional or three-dimensional components.
To meet such a demand, there has been proposed a force detector in which gauge resistors are formed on a semiconductor substrate such as silicon, etc. to transform a mechanical distortion produced in the substrate on the basis of a force applied from the external to an electric signal by making use of the piezo resistive effect. When a weight body is attached to the detecting unit of the force detector, an acceleration detector for detecting, as a force, an acceleration applied to the weight body can be realized. Further, when a magnetic body is attached to the detecting unit of the force detector, a magnetic detector for detecting, as a force, a magnetism exerted on the magnetic body can be realized.
For example, in U.S. Pat. No. 4,905,523, U.S. Pat. No. 4,967,605, U.S. Pat. No. 4,969,366, U.S. patent application Ser. No. 07/362,399, Ser. No. 07/470,102, and Ser. No. 07/559,381, force detectors using gauge resistor, acceleration detectors, and magnetic detectors are disclosed. Further, in U.S. patent application Ser. No. 07/526,837, a manufacturing method suitable for these detectors is disclosed.
Since there generally exists temperature dependency in the gauge resistance or the piezo resistive coefficient, in the case of the above described detectors, if there occurs any change in the temperature of the environment where those detectors are used, a detected value would include an error. Accordingly, it is required for carrying out a precise measurement to conduct temperature compensation. Particularly, in the case where such detectors are used in the field of automotive vehicle, etc., temperature compensation is required over the considerably broad operating temperature range of −40 to +12° C.
In addition, in order to manufacture the above described detectors, a high level process for processing the semiconductor substrate is required, and a high cost apparatus such as an ion implanter is also required. For this reason, there is the problem that the manufacturing cost becomes high.